The object of the proposed research is to apply recently developed methods for forming beta-lactams to the synthesis of antibiotics in the beta-lactam field. Beta-lactams will also be employed as intermediates in the synthesis of macrocyclic lactams. In this work we will explore new routes to the formation of (3.2.0) azaheptenes present in the thienamycin such as the Diels-Alder addition of 1,4-dienes to azetines, followed by suitable ring contraction. Work on this aspect of the research will require the development of new methods for the formation of azetine carboxylates or of suitable precursors capable of yielding the unsaturated four-membered unit in situ. A second aspect of the research will be aimed at the use of substituted beta-lactams as intermediates in the formation of the spermidine alkaloids. Our plan is to utilize the intramolecular ring opening of beta-lactams for the construction of large rings. In particular, we will use the methodology developed in our recent syntheses of homaline, celacinnine and dihydroperiphylline for the formation of more complex polyamine natural products such as ephedradine A and chaenorhine.